ABSTRACT
This chapter focuses on the posttranscriptional modification of Apolipoprotein B (apo B) mRNA referred to as apo B mRNA editing. Mammalian apo B is expressed in a tissue-specific manner with gene transcription and protein synthesis predominantly confined to the adult liver and small intestine. The topology of apo B mRNA editing in other cell types, particularly the small intestine, has not been evaluated, at least in part because of difficulties associated with the preparation of intestinal nuclei and intact nuclear RNA. Thyroid hormone modulation of hepatic apo B mRNA editing was accompanied by striking alterations in hepatic lipid mobilization. Apo B mRNA editing was demonstrated to be both a developmentally regulated event and to be modulated in the adult animal following hormonal manipulation. The relatively low level of in vitro apo B mRNA editing observed with McA7777 cells has been observed by others in nuclear extracts prepared from rat liver.
